Protective laminates

ABSTRACT

Protective laminates are provided that include (a) a layer that is breathable and highly impermeable to chemicals to a degree that is subject to reduction upon flexing of the highly impermeable layer alone; and (b) a breathable non-textile layer attached to the highly impermeable layer, the non-textile layer mitigating the reduction in the impermeability of the highly impermeable layer if the laminate is flexed. The laminates may, for example, be attached to textiles and used in protective fabrics.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part (and claims the benefit ofpriority under 35 USC 120) of U.S. application Ser. No. 10/732,554 filedDec. 10, 2003. The disclosures of the prior application is consideredpart of (and is incorporated by reference in) the disclosure of thisapplication.

TECHNICAL FIELD

This invention relates to protective laminates.

BACKGROUND

Protective garments, e.g., garments used by emergency workers, aregenerally made of fabrics that protect the wearer from the conditionsthe wearer expects to encounter, e.g., heat and flame in the case offirefighting garments. The fabrics used in such garments are typicallywaterproof and allow water vapor to pass from inside to outside thegarment to provide comfort to the wearer during periods of exertion. Anexample of a waterproof breathable laminate produced from an expandedpolytetrafluoroethylene (“ePTFE”) membrane is disclosed in U.S. Pat. No.4,194,041. In this structure, the pores of the ePTFE are protected by ahydrophilic polyurethane layer, to prevent the pores of the ePTFE frombecoming contaminated by lower surface energy liquids. Lower surfaceenergy liquids tend to wet out untreated microporous structures, therebyreducing the hydrostatic resistance of the membrane and correspondinglaminate structure.

Fabrics for protective garments may include a textile layer and a layerof a protective film that provides waterproofing. The protective filmmay be, for example, a treated micro-porous film, e.g., a film such asePTFE as described in U.S. Pat. No. 4,194,041 above that has pores sizedto permit vapor molecules to pass, while blocking water molecules, buthas its surface energy modified to reduce its ability to wet out.Alternatively, the protective film could be a monolithic layer producedfrom a hydrophilic material such as polyurethane, nylon, or polyetherblock amides such as the polymer sold by Arkema under the trademarkPEBAX®.

In many applications, it is necessary that the fabric be highlychemically resistant. For example, the Standard on Protective Ensemblefor Structural Fire Fighting published by the National Fire ProtectionAgency (NFPA 1971, 2000 Edition) require the moisture barrier layer offire fighting garments to resist penetration by a list of chemicals inaccordance with ASTM F903 (Standard Test Method for Resistance ofProtective Clothing Materials to Penetration by Liquids). Otherapplications, such as military applications and hazardous wasteclean-up, also require high chemical resistance, but known laminates maynot allow for effective transport of moisture, leading to heat stress.

It is important that fabrics used in protective garments be capable ofwithstanding laundering without loss of chemical resistance or, iflaminated to a textile, to have resistance to de-lamination of theprotective film from the textile.

SUMMARY

The inventors have found that certain chemically resistant breathablefilms are relatively brittle and may fracture easily when flexed undercertain conditions. This brittleness may render fabrics including suchfilms subject to a decrease in chemical impermeability after laundering,due to the impact of the wet environment of laundering on the physicalproperties of the film. Some chemically resistant breathable films arealso subject to a decrease in their impermeability as a result offlexing under dry conditions. The inventors have addressed this problemby providing protective laminates including a highly impermeable layerand a non-textile layer that tends to mitigate the reduction in theimpermeability of the highly impermeable layer if the laminate isflexed.

In one aspect, the invention features a protective laminate thatincludes (a) a layer that is breathable and highly impermeable to one ormore chemicals to a degree that is subject to reduction as a result offlexing of the highly impermeable layer alone; and (b) a hydrophilicnon-textile layer attached to the highly impermeable layer, thenon-textile layer mitigating the reduction in the impermeability of thehighly impermeable layer that is a result of flexing of the laminate.

The term “breathable,” as used herein, refers to the moisture vaportransmission rate (MVTR) of a material. A breathable film preferably hasa MVTR of at least 200 g/m²/day, measured by ASTM E96B.

The phrase “highly impermeable to one or more chemicals,” as usedherein, means that the layer would significantly inhibit the flow ofharmful chemicals from one side of the layer to the other. This phrasedoes not mean that the layer is necessarily impermeable to all fluids;for example, it may be permeable to water vapor. Preferably,impermeability is sufficient to comply with the liquid penetrationresistance requirement associated with NFPA 1971, 2000 edition. Somehighly impermeable layers may also comply with the chemical permeationresistance test required by NFPA 1994, as tested according to ASTM F739.

The phrase “subject to reduction upon flexing of the highly impermeablelayer alone,” means that if the highly impermeable layer is not attachedto the non-textile layer, the chemical resistance of the highlyimpermeable layer will be deleteriously affected by flexing the highlyimpermeable layer. In some cases, the reduction in chemical resistancemay occur after only a single flexing.

The term “non-textile” refers to an organic polymeric sheet materialthat is not manufactured from fibrous materials, and excludes, forexample, woven and non-woven fibrous sheet materials, but includes, forexample, polymeric film materials such as ePTFE which, although havingsome fibrous character, i.e., a fine structure of interconnected nodesand fibrils, is made using PTFE fine powder.

The phrase “mitigating the reduction in the impermeability” means thatthe reduction in impermeability that would occur upon flexing of thehighly impermeable layer alone is reduced to a measurable extent whenthe protective laminate is tested, before and after repeated flexing,under the same conditions using the same test procedure. Testing may beperformed, for example, using a Newark Flexing Machine according to thetest procedures specified in ASTM D2097, under the environmentalconditions specified in ASTM D1610.

The term “layer” refers to a discrete region of material, which, unlessotherwise noted (e.g., by specifying that the layer is free-standing),may be in the form of a continuous film, coating, deposit, or any otherdesired form.

Some implementations include one or more of the following features. Thelaminate may further include a second non-textile layer, and the highlyimpermeable layer may be interposed between the non-textile layers.Alternatively, the laminate may further include a second highlyimpermeable layer, and the non-textile layer may be interposed betweenthe highly impermeable layers. The laminate may further include atextile layer attached to the highly impermeable layer or thenon-textile layer, e.g., to form a protective fabric. The protectivelaminate may have a MVT of at least 200, preferably at least 2000. Thelayers may each individually have a MVT of at least 200. The layers mayeach be microporous or monolithic. The highly impermeable layer may havea thickness of about 5 to about 50 μm. The non-textile layer may have athickness of about 1 to about 50 μm. The laminate may further include anadhesive layer attaching the non-textile layer to the highly impermeablelayer. The adhesive layer may be discontinuous. Alternatively, thenon-textile layer may be bonded directly to the highly impermeablelayer, without intervening adhesive. The non-textile layer may comprisea free-standing film, for example a film selected from the groupconsisting of polyurethane films, expanded PTFE films, polyester films,nylon films, polyether block amide films, and polyethylene films. Thenon-textile layer may be hydrophilic.

In a further aspect, the invention features a protective laminateincluding (a) a layer that is breathable, and highly impermeable tochemicals to a degree that is subject to reduction upon flexing of thehighly impermeable layer alone; (b) a non-textile layer attached to thehighly impermeable layer, the non-textile layer mitigating the reductionin the impermeability of the highly impermeable layer if the laminate isflexed; and (c) a second non-textile layer, wherein the highlyimpermeable layer is interposed between the non-textile layers.

The invention also features protective laminates that include a firstlayer that includes a fluorinated ion exchange polymer, and a breathablehydrophilic polymer layer attached to the first layer.

In another aspect, the invention features a method including bonding alayer that is breathable and highly impermeable to chemicals to a degreethat is subject to reduction upon flexing of the highly impermeablelayer, to a breathable, hydrophilic non-textile layer, the non-textilelayer mitigating the reduction in the impermeability of the highlyimpermeable layer if the laminate is flexed.

Some implementations may include one or more of the following features.The bonding step may include applying an adhesive to one or both layers.The adhesive may be applied in a discontinuous pattern. The adhesive maybe applied in a continuous pattern using a hydrophilic polymer. Theadhesive may be applied by gravure printing. The bonding step mayinclude thermally bonding the non-textile layer directly to the highlyimpermeable layer.

The invention also features other methods of forming the laminatesdescribed above by bonding together the various layers of the laminates,and laminates that include the features described herein in any desiredcombination.

In a further aspect, the invention features articles made with theprotective laminates. For example, the invention features an articleincluding: (a) a protective laminate that includes (i) a layer that isbreathable and highly impermeable to chemicals to a degree that issubject to reduction upon flexing of the highly impermeable layer alone;and (ii) a breathable non-textile layer attached to the highlyimpermeable layer, the non-textile layer mitigating the reduction in theimpermeability of the highly impermeable layer if the laminate isflexed; and (b) a textile layer, attached to the protective laminate toform a chemically resistant fabric, the chemically resistant fabricbeing configured to define the article.

The article may be, for example, a protective structure such as a tent,a garment such as a jacket, pair of pants or glove, or an insert forfootwear.

Among the advantages of the invention may be one or more of thefollowing.

In some implementations, the protective laminates are selectivelypermeable, i.e., they exhibit high moisture vapor transmission rates,while also being able to restrict the passage of harmful chemicals,preferably under conditions where a pressure differential exists. Thelaminates may be attached to a textile layer for use in articles such asprotective garments, tents and accessories that may be subjected toadverse conditions. Some laminates, when attached to a textile layer,provide excellent chemical resistance even after repeated launderingsand/or other flexing such as may occur during use of a garment. In someimplementations, fabrics including the protective laminate meet NFPAstandards for flame-retardancy and chemical resistance. The laminatesare waterproof and breathable. In some cases, the laminates may meet therequirements of the chemical permeation resistance test required by NFPA1994, as tested according to ASTM F739. The laminates can be producedrepeatably and predictably. The laminates are easily stored, shipped,and manipulated during lamination to a textile layer. The barrierproperties of the laminate are maintained prior to lamination to atextile layer. In certain applications, such as semi-durable and durablegarments, it is useful to achieve resistance to water penetration andprovide chemical resistance after multiple launderings. In militaryapplications, a minimum of 6 wash/dry cycles is typically requested,whereas in the Fire Service the chemical penetration testing is doneafter 5 wash/dry cycles complying with a procedure specified in AATCC135. Fabrics produced with some protective laminates may protect thewearer of a garment or contents of a protective structure from noxiousgases, such as Sarin, Mustard, and VX nerve agents and other noxiouschemical agents. Fabrics produced with some protective laminates mayshow no evidence of penetration of a solution consisting of 75%diethyltoluamide (DEET) and 25% ethanol before and after laundering whentested according to paragraphs 4.4.2.6 and 4.4.14 of MIL-DTL-31011A.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features andadvantages of the invention will be apparent from the description anddrawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a diagrammatic, highly enlarged exploded side view of aprotective fabric including a protective laminate.

DETAILED DESCRIPTION

A fabric 10, for use, e.g., in a protective garment, is showndiagrammatically in FIG. 1. Fabric 10 includes a protective laminate 12and a textile layer 14. In this embodiment, protective laminate 12includes a highly impermeable layer 16 interposed between twonon-textile layers 18 and 20. While the layers of fabric 10 are explodedin FIG. 1, for clarity, in the finished fabric all of the layers wouldbe attached to each other, e.g., by adhesive or lamination as will bediscussed below. Typically, one of the layers of the protective laminateis attached to a textile, forming a preliminary laminate, and then theother layers are applied to this preliminary laminate. However, ifdesired all of the layers can be laminated together in a singleprocessing step or in a different order of steps.

Highly impermeable layer 16 may be a free-standing film prior to beingattached to the non-textile layers. Suitable highly impermeable layersare highly impermeable to chemicals. It is generally preferred that thehighly impermeable layer comply with the liquid penetration resistancerequirement associated with NFPA 1971, 2000 edition.

Suitable highly impermeable layers may be relatively brittle, and thustend to exhibit a reduction in chemical impermeability when flexed, asdiscussed above. For example, the highly impermeable layer, when testedalone, may exhibit visually observable cracking after 50 to 500 cyclesusing a Newark Flex Tester according to the test procedure specified inASTM D2097, under the environmental conditions specified in ASTM D1610.The highly impermeable layer typically has a thickness of less thanabout 50 μm, e.g., from about 5 to 50 μm.

Suitable barrier films are breathable, i.e., they have an MVTR of atleast 200 g/m²/day, measured by ASTM E96B. In some implementations, thehighly impermeable layer has an MVTR of from about 200 to 5000. Thehighly impermeable layer may be monolithic or microporous.

One suitable highly impermeable layer is a polyether sulfone (PES) filmthat is treated with a fluoropolymer to modify its surface energy,commercially available from Pall Corp. under the tradename SUPOR.Another suitable highly impermeable layer is a film of fluorinated ionexchange polymer, such as the film commercially available from DuPontunder the trademark NAFION®.

The fluorinated ion exchange polymer employed in accordance with thisinvention preferably has anionic functionality, most preferablysulfonate functional groups, which may be in the hydrogen ion, ammoniumion, or metal ion form. Preferably, the polymer is in metal ion orhydrogen ion (proton) form in the garment, more preferably the sodiumion form or the hydrogen ion form. Preferably, the polymer comprises apolymer backbone with recurring side chains attached to the backbone,the side chains carrying the ion exchange groups. Preferably, there isat least one and more preferably two fluorine atoms attached to thecarbon atom of the side chain to which the ion exchange group isattached. It is especially preferable to employ “highly fluorinated” ionexchange polymer. By “highly fluorinated” is meant that in the polymerin ion exchange form at least half the monovalent atoms bound to carbonatoms are fluorine atoms. The fluorinated ion exchange polymers can becopolymers of fluorinated monomers containing the sulfonic functionalgroup with nonfunctional monomers, usually the predominant monomer inthe polymer, referred to herein as fluoromonomer-based polymers.Examples of fluorinated monomers containing the sulfonic functionalgroup (in precursor form) are the perfluorinated vinyl ethersCF₂═CF—O—CF₂CF(CF₃)—O—CF₂CF₂SO₂F,perfluoro(3,6-dioxa-4-methyl-7-octenesulfonyl fluoride) andCF₂═CF—O—CF₂CF₂SO₂F, perfluoro(3-oxa-4-pentenesulfonyl fluoride).Examples of nonfunctional fluoromonomers are tetrafluoroethylene,trifluoroethylene, vinylidene fluoride, vinyl fluoride andchlorotrifluoroethylene. The polymers employed in accordance with thepresent invention are preferably tetrafluoroethylene-based polymers,i.e., where the nonfunctional monomer is predominatelytetrafluoroethylene. Most preferably, the polymers employed areperfluorinated. By perfluorinated is meant that substantially all themonovalent atoms bound to carbon atoms on the backbone of the polymer(the main chain) are fluorine atoms. Some of the monovalent atoms boundto carbon atoms at the end of the main chain may be hydrogen atoms, suchas might be derived from chain transfer agents. Such polymers and theirpreparation are well-known in the art, and are described in U.S. Pat.Nos. 3,282,875, 4,358,545 and 4,940,525. In addition to having goodwater vapor transport properties, such polymers are unaffected by manyof the chemicals used in decontamination of protective garments.

The fluorinated ion exchange polymer is characterized by equivalentweight, that is, the weight in grams of polymer in the hydrogen ion formthat neutralize one equivalent of base, such as sodium hydroxide. Theequivalent weight of fluorinated ion exchange polymer of this inventionis about 500 to 1500, preferably about 700 to 1300, more preferablyabout 800 to 1200, still more preferably about 850 to 1150, and mostpreferably about 900 to 1100.

The fluorinated ion exchange polymer film used in making the highlyimpermeable layer may be prepared by extrusion of fluorinated ionexchange polymer. This is done with the polymer in a melt processibleprecursor form (the hydrogen ion or other ionic forms of fluorinate ionexchange polymers are not easily melt processed). The usual form formelt processing of a polymer having sulfonate functional groups is thesulfonyl fluoride form. After melt processing, the sulfonyl fluoride canbe hydrolyzed to the sulfonic acid salt form by treatment with aqueousbase, preferably potassium hydroxide (KOH), and preferably in thepresence of a cosolvent, such as dimethyl sulfoxide (DMSO). A typicalformulation is 10-15 wt % KOH, 10-15 wt % DMSO, and the balance water.Typical hydrolysis times and temperatures are 15-60 minutes at 50-90° C.The resulting fluorinated ion exchange polymer is in the potassium saltform and may be converted to other ionic forms by ion exchange with theappropriate solutions, e.g. 10-20 wt % aq. nitric acid if the hydrogenion form is desired, 10-20 wt % aq. sodium chloride solution for thesodium ion form. After treatment, the film is washed with deionizedwater several times and dried at temperatures not exceeding about 150°C., preferably not exceeding 100° C.

Alternatively, the film can be made by casting an aqueous alcoholicsolution of Nafion®, available from Aldrich Chemical Co. Milwaukee Wis.or DuPont Company, Wilmington Del. The solution dries to form film inthe hydrogen ion form. This may be ion exchanged to make other ionicforms. Ion exchange is accomplished using an aqueous solution of from 1to 10 wt % of a salt, oxide, or hydroxide of the desired cation, such assodium chloride or sodium hydroxide if the sodium ion form is wanted.Oxides or hydroxides are preferred under conditions where their more orless high alkalinity can be tolerated. For ion exchange of the film whenit is adhered to fabric, salt is preferred as less likely to affect thefabric adversely. Exchange is rapid, 0.5 to 10 hours being enough time.The exchanged film (and fabric if present) is rinsed 2 to 3 times inwater to removes excess salt or hydroxide. All this is done at roomtemperature.

The highly impermeable layer can be a composite of fluorinated ionexchange polymer on a porous support. One such a composite is expandedpolytetrafluoroethylene (ePTFE), Goretex® is an example, impregnatedwith fluorinated ion exchange polymer. Composites of this type aredisclosed in U.S. Pat. Nos. 5,547,551 and 5,599,614. A composite offluorinated ion exchange polymer film adhered to ePTFE is disclosed inU.S. Pat. No. 5,082,472. This structure may additionally be partially orcompletely impregnated with fluorinated ion exchange polymer.

A suitable highly impermeable layer is a perfluorosulfonic acid film(tetrafluoroethylene/perfluoro (4-methyl-3,6-dioxa-7-octene-1-sulfonicacid) copolymer), CAS Number 31175-20-9, such as that sold by DuPontunder the trademark NAFION®. The NAFION® films have a tensile modulus(ASTM D 882) at 23° C. and 50% RH of about 249 MPa, a tensile modulus at23° C. when water soaked of about 114 MPa, and a tensile modulus at 100°C. when water soaked of about 64 MPa. The elongation at break (ASTM D882) shows a similar decrease when the films are water soaked. TheNAFION® films exhibit an elongation at break at 23° C. and 50% RH ofabout 225% in the machine direction and 310% in the transverse(cross-machine) direction, an elongation at break at 23° C. when watersoaked of about 200% in the machine direction and 275% in the transversedirection, and an elongation at break at 100° C. when water soaked ofabout 180% in the machine direction and 240% in the transversedirection. Other properties of the NAFION® films include an MVTR ofabout 4000 g/m²/day, and a thickness of about 1 to 100 μm, typicallyabout 5 to 50 μm.

The non-textile layers 18 and 20 may be the same or different. One orthe other of the non-textile layers may be omitted. Thus, the protectivelaminate may include only inner non-textile layer 18, leaving highlyimpermeable layer 16 exposed (i.e., the fabric 10 includes an innernon-textile layer 18 interposed between a highly impermeable layer 16and a textile layer 14), or the protective laminate may include onlyouter non-textile layer 20, so that the highly impermeable layer 16 isin direct contact with the textile layer 14 in the finished fabric(i.e., the fabric 10 includes a highly impermeable layer 16 interposedbetween an outer non-textile layer 20 and a textile layer 14). Otherconfigurations may also be possible.

Suitable materials for use in the non-textile layer(s) include films andother materials that will mitigate the reduction in chemicalimpermeability of the highly impermeable layer when the protectivelaminate is flexed. Preferred non-textile layer materials willsubstantially eliminate the reduction in impermeability over a largenumber of flex cycles, i.e., will mitigate the reduction inimpermeabilty sufficiently so that the protective laminate will stillpass the liquid penetration resistance requirement associated with NFPA1971, 2000 edition even after repeated flexing. The non-textile layerincreases the number of flex cycles prior to visually observablecracking by at least about 10%, preferably at least about 50%, and morepreferably at least about 100%, in comparison to the highly impermeablelayer alone as measured under comparable test conditions, such as samplethickness. The use of non-textile layers on both sides of the highlyimpermeable layer increases the number of flex cycles by at least about50%, preferably at least about 200%, more preferably at least about500%, and most preferably at least about 1000%. In some implementations,the use of non-textile layers on both sides of the highly impermeablelayer is preferred.

The non-textile layer typically has a thickness of less than about 70μm, and preferably is from about 0.001 to 0.050 mm thick, morepreferably, about 0.002 to 0.025 mm thick.

Suitable materials for use as non-textile layers are breathable, i.e.,have an MVTR of at least 200 g/m²/day, measured by ASTM E96B. It isgenerally preferred that the breathability of the non-textile layer besimilar to or greater than that of the highly impermeable layer. Thus,the breathability of the non-textile layer is generally in the range ofabout 200 to 5000. If desired, the layers of the laminate may havedifferent levels of breathability, provided the overall breathability ofthe laminate is adequate for its intended use. The non-textile layer maybe monolithic or microporous, and may be a film or other continuous ordiscontinuous sheet material. When the protective laminate includes twonon-textile layers, as shown in FIG. 1, one can be monolithic and theother can be microporous, or both can be monolithic or microporous.

In some implementations, the polymers for the non-textile layer arehydrophilic. Hydrophilic polymers transfer substantial amounts of watervapor through a film of the polymer by absorbing water on one side ofthe film where the water concentration is high, and desorbing orevaporating it on another side where the water concentration is lower.

Suitable materials for non-textile layers are sufficiently flexible atthe thickness employed to be suitable for the particular end useapplication. In some cases, the polymer of the non-textile layer iselastomeric. The term “elastomer” as used herein means a polymer whichexhibits rapid and nearly complete recovery from an extending force.Elastomer can be stretched to about 100% without breaking. After suchstretch and being held for about 5 minutes and then released, theelastomer will retract to within about 10% of its original length withinabout 5 minutes after release.

Preferred materials for non-textile layers facilitate secure attachmentof textiles layers to the laminate, i.e., by attaching the textile tothe non-textile layer. With some highly impermeable layers such asfluorinated ion exchange polymer, sufficiently secure attachment to thehighly impermeable layer to endure repeated wash cycles is difficult toachieve. In addition, preferred non-textile layers can also assist withsecure attachment at seams to enable the seams to be adequately sealed.

A preferred non-textile layer is made of hydrophilic polyurethane orpolyether block amide. An example of a suitable hydrophilic polyurethanefilm is TX1540 film, commercially available from Omniflex under thetradename TRANSPORT. This film is a hydrophilic polyurethane, having a100% modulus of about 550-650 psi and a thickness of about 0.5-25 p.m.An example of a suitable polyether block amide layer is TX4100 filmcommercially available from Omniflex.

Other suitable films for use as non-textile layers include otherhydrophilic polyurethane films, e.g., TX1530 film, commerciallyavailable from Omniflex; microporous polyurethane, e.g., P3 series filmscommercially available from Porvair; expanded polytetrafluoroethylene(ePTFE), e.g., ePTFE films commercially available from W.L. Gore,Tetratec and BHA; hydrophilic co-polyester films, e.g., SYMPATEX filmsfrom Sympatex Technologies and HYTREL films from DuPont;polyamide-elastomer alloy films, e.g., TX3050 films commerciallyavailable from Omniflex; other polyether block amide films, e.g., filmsformed from PEBAX resins (Arkema); and microporous polyolefin films,e.g., microporous polyethylene films. Other suitable hydrophilicpolyurethane films include films formed from 58245 resin, commerciallyavailable from Noveon.

In most cases, the non-textile layer will have a lesser degree ofchemical impermeability to certain chemicals than the highly impermeablelayer. In such cases, the non-textile layer may not, by itself, haveadequate chemical impermeability for use in the application for whichthe protective laminate is intended.

The textile layer may be any desired textile, including woven, knittedand nonwoven materials and composites of such materials. The textile maybe selected based on the properties required for a given application,e.g., flame and/or heat resistance, thermal properties, comfort, weight,and moisture vapor transmissivity. Suitable textiles include 332N NOMEX®fabric, available from Southern Mills, NYCO fabric, available in acamouflage print from Bradford Dye, and 70d taslanized nylon. Othersuitable textiles include nonwovens such as VILENE® nonwoven,commercially available from Freudenberg, and E89™ nonwoven, commerciallyavailable from DuPont. The textile layer generally has a thickness offrom about 0.1 to 1.0 mm. The textile layer generally does notcontribute significantly to the mitigation of the loss of chemicalimpermeability of the highly impermeable layer, but does frequentlyoffer physical protection against abrasion tear and puncture.

The fabric 10 (textile layer and protective laminate) will typicallyhave an MVTR of at least 200 g/m²/day as measured by ASTM E96B. In someimplementations, the MVTR will be from about 200 to 5000 g/m²/day, e.g.,from about 1000 to 3000 g/m²/day. The fabric 10 will generally complywith the liquid penetration resistance requirement associated with NFPA1971, 2000 edition, and with other industry standards regardingimpermeability, for example chemical penetration after launderingaccording to the laundering procedure specified in AATCC 135.

Various techniques may be used to join the layers of the protectivelaminate, and to join the protective laminate to the textile layer. Forexample, the non-textile layer(s) may be bonded to the highlyimpermeable layer using an adhesive, such as a solvent basedcrosslinking polyurethane adhesive, a reactive hot melt-polyurethaneadhesive, or a thermoplastic adhesive, e.g., a thermoplastic polyester,polyurethane, nylon or olefinic adhesive supplied, for example, as a hotmelt, film, or powder- or web-based system. When the highly impermeablelayer comprises fluorinated ion exchange polymer, it is preferred thatthe fluorinated ion exchange polymer be in the hydrogen ion (proton)form as this form allows better adhesion of other layers to the highlyimpermeable layer.

The adhesive may be applied as a discontinuous layer to one or both ofthe layers to be adhered, e.g., using direct gravure printing. Thediscontinuous adhesive may be applied in any desired pattern, e.g.,lines, dots, polygons, or other shapes. Suitable methods for applying anadhesive in a discontinuous pattern are described, for example, in U.S.Pat. No. 5,874,140, the disclosure of which is incorporated by referenceherein.

Alternatively, the layers may be thermally fused or pressure laminated,without any intervening adhesive. The process parameters for thisoperation will vary depending on the materials used for the non-textileand highly impermeable layers, and would be selected to provide goodadhesion without significant damage or deterioration of any of thelayers.

The following examples are intended to be illustrative and not limitingin effect.

Example 1

A protective laminate was formed using a multi-pass process, as follows:

Pass 1: A barrier film (0.019 mm perfluorosulfonic acid, commerciallyavailable from DuPont under the tradename NAFION®) was laminated to awoven textile layer known in the trade as NYCO and manufactured from ablend of cotton, nylon and a small percentage of carbon fiber. The filmwas printed with a solvent-based crosslinking polyurethane adhesivesystem having a viscosity of 15,000 to 25,000 cps on a gravureapplicator with a discontinuous dot pattern. The film and textile layerwere combined in a nip at a processing speed of 10 to 20 yards perminute. The adhesive was then allowed to cure for a few days.

Pass 2: The film side of the barrier/textile laminate created in Pass 1was printed with adhesive as described above in Pass 1, and thebarrier/textile laminate was combined with a non-textile layer (a 0.005mm hydrophilic polyurethane film having a Shore hardness of 80 A and a100% modulus of 550-650 psi, commercially available from Omniflex underthe tradename Transport TX1540) at a processing speed of 10 to 20 yardsper minute.

Example 2

A laminate was made as discussed in Example 1 above, except that in Pass1 the barrier film used was a polyether sulfone (PES) film that istreated with a fluoropolymer to modify its surface energy, commerciallyavailable from Pall Corp. under the tradename SUPOR.

Example 3

To test the effect of providing a non-textile layer on the flexuralproperties of highly impermeable layers, the non-textile layer describedabove in Example 1 was laminated to one side and to both sides of thebarrier films described in Examples 1 and 2. The textile layer wasomitted.

These laminates were flex tested through multiple flexing cycles using aNewark Flexing Machine according to the procedure specified in ASTMD2097, under the ambient conditions specified in ASTM D1610. As acontrol, the two highly impermeable layers were individually subjectedto the same testing. The samples were observed visually, and were deemedto have failed on the cycle at which the first visually observablecracking occurred.

The results of this testing were as follows: the NAFION highlyimpermeable layer alone withstood 87 cycles, while the PES highlyimpermeable layer alone withstood 394 cycles. Adding a singlenon-textile layer increased the number of cycles before failure by 887%and 33%, respectively. Adding non-textile layers on both sides of thebarrier film increased the number of cycles before failure by 1817% and599%, respectively.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.

For example, while the non-textile layer has been described above as afilm, in some cases the non-textile layer may be a coating. The coatingmay be formed by applying a liquid directly to the highly impermeablelayer, or by casting the liquid onto a release surface and thentransferring the cast coating from the release surface to the highlyimpermeable layer. The liquid may be a polymeric solution. For example,a polymer such as a thermoplastic polyurethane, e.g., polymerscommercially available from Noveon under the designations 58245 or58237, may be solvated and the solution may be cast and transferred asdescribed above. Suitable coatings include, for example, hydrophilicpolyurethane systems, such as the HYPOL series available from DowChemical or COMFORTEX 52158, available from Raffi & Swanson. The typicalapplication weight is generally from about 0.2 oz/sq.yd. to 1.0oz/sq.yd.

Alternatively, the non-textile layer may be provided as a film and thehighly impermeable layer may be formed by applying a coating of liquidsolution or dispersion of the highly impermeable layer polymer directlyto the non-textile layer.

Moreover, in addition to the arrangements discussed above (non-textilelayers on one or both sides of a single highly impermeable layer) otherarrangements are possible. For example, a single non-textile layer canbe interposed between two highly impermeable layers, e.g., if it isdesirable to, protect the non-textile layer from exposure to chemicals.One or more additional non-textile and/or highly impermeable layers maybe included in any of these arrangements. Also, while a single textilelayer is shown in FIG. 1 and described above, the fabric may includemultiple textile layers on a single side of the protective laminate, orthe protective laminate may be interposed between multiple textilelayers.

The resulting fabric can be used in any desired manner. For example, thefabric can be cut according to a pattern, and the patterned pieces canthen be sewn to form a garment. The fabrics are suitable for use inprotective garments. In some implementations, the fabrics are suitablefor use in garments for applications such as firefighting, hazardouswaste cleanup, and environmental remediation.

Accordingly, other embodiments are within the scope of the followingclaims.

1. A protective laminate comprising a layer that is breathable, andhighly impermeable to chemicals to a degree that is subject to reductionupon flexing of the highly impermeable layer alone; and a breathablehydrophilic non-textile layer attached to the highly impermeable layer,the non-textile layer mitigating the reduction in the impermeability ofthe highly impermeable layer if the laminate is flexed.
 2. Theprotective laminate of claim 1 further comprising a second non-textilelayer, wherein the highly impermeable layer is interposed between thenon-textile layers.
 3. The protective laminate of claim 1 furthercomprising a second highly impermeable layer, wherein the non-textilelayer is interposed between the highly impermeable layers.
 4. Theprotective laminate of claim 1 further comprising a textile layerattached to the highly impermeable layer.
 5. The protective laminate ofclaim 1 further comprising a textile layer attached to the non-textilelayer.
 6. The protective laminate of claim 1 wherein the highlyimpermeable layer comprises a fluorinated ion exchange polymer.
 7. Theprotective laminate of claim 1 wherein the non-textile layer comprisesan elastomeric polymer.
 8. The protective laminate of claim 1 whereinthe non-textile layer comprises a polymer selected from the groupconsisting of polyurethane, copolyester, polyether block amide,polyamide-elastomer alloy, and mixtures thereof.
 9. The protectivelaminate of claim 1 wherein the non-textile layer comprisespolyurethane.
 10. The protective laminate of claim 1 wherein theprotective laminate has a MVT of at least
 2000. 11. The protectivelaminate of claim 1 wherein the highly impermeable layer is microporous.12. The protective laminate of claim 1 wherein the highly impermeablelayer is monolithic.
 13. The protective laminate of claim 1 wherein thenon-textile layer is microporous.
 14. The protective laminate of claim 1wherein the non-textile layer is monolithic.
 15. The protective laminateof claim 1 wherein the highly impermeable layer has a thickness of about1 to 100 μm.
 16. The protective laminate of claim 1 wherein thenon-textile layer has a thickness of about 1 to 50 μm. 17-67. (canceled)